Rydberg Molecule--strange first

Back in 1934 Enrico Fermi predicted that if another atom were to "find" that lone, wandering electron, it might interact with it but he never imagined that molecules could be formed.
Recently Vera Bendkowsky and his team from the University of Stuttgart created such a molucle known as a Rydberg molecule; this is formed through an elusive and extremely weak chemical bond between two atoms.
The Rydberg molecules in question were formed from two atoms of rubidium - one a Rydberg atom, and one a "normal" atom.
The movement and position of electrons within an atom can be described as orbiting around a central nucleus - with each shell of orbiting electrons further from the centre.
A Rydberg atom is special because it has one electron alone in an outermost orbit - very far, in atomic terms, from its nucleus.
Unimaginably cold temperatures are needed to create the molecules.At temperatures very close to absolute zero - minus 273C - this "critical distance" of about 100nm (nanometres - 1nm = one millionth of a millimetre) between the atoms is reached.
When one is a Rydberg atom, the two atoms form a Rydberg molecule. This 100nm gap is vast compared to ordinary molecules
Pushing this electron out to its lonely periphery - and make a Rydberg atom - requires energy.
This ultracold experiment is also ultra-fast - the longest lived Rydberg molecule survives for just 18 microseconds.
But the fact that the molecules can be made and seen confirms long-held fundamental atomic theories.